Security integrated circuits, commonly known as “security chips”, are often used to protect information, data transmissions, access control, or value (typically monetary). Data in security chips is typically protected through the use of secure memory and/or the secure transmission of data using cryptographic techniques implemented on chip. Some applications for security chips include: banking cards, television conditional access system cards, premises access control cards, personal identity cards, USB flash drives and automobile keys.
“Crackers”, people who use their expertise to illegally break into secure programs and systems, have been known to remove security chips from their packaging and then to connect the security chips to suitable electrical connections in such a way that the chips remains operational. In this fashion the crackers can more easily study and reverse engineer operating security chips, thereby greatly compromising the security of the security chips. The terms “crack” and “hack,” in their various grammatical forms, are used interchangeably in the present application.
Various methods of invasive attack on chips are known in the art, whereby crackers, criminals, and others try to obtain, change, or use secret information on the chips. There are also various methods known in the art, which attempt to protect chips from these various forms of invasive attack. Most such known protection methods are easily circumventable by those skilled in the art of cracking.
The following references provide general background in the field of the invention:
U.S. Pat. No. 5,159,629 to Double et al;
U.S. Pat. No. 5,910,774 to Capriotti et al;
U.S. Pat. No. 6,360,321 to Gressel et al;
U.S. Pat. No. 6,429,640 to Daughton et al;
U.S. Pat. No. 7,005,733 to Kommerling et al;
US Published Patent Application US20050236683 of Shapiro et al;
US Published Patent Application US20060081497 of Knudsen et al;
Japan Published Patent Application JP2002082135 of Yazaki Corp;
Japan Published Patent Application JP2002082136 of Yazaki Corp;
PCT Published Patent Application WO 05/114733 of NDS Ltd and corresponding U.S. patent application Ser. No. 10/593,386
www.nve.com/Downloads/apps.pdf
qdev.boulder.nist.gov/817.03/whatwedo/magsensors/Dave-%20Magnetic %20 Sensor %20Applications %20 Workgroup.doc
“CMOS Integrated DNA Microarray Based on GMR Sensors”, Shu-Jen Han, Liang X U, Heng Yu, et al
www.pcguide.com/ref/hdd/op/heads/techGMR-c.html
The disclosures of all references mentioned above and throughout the present specification, as well as the disclosures of all references mentioned in those references, are hereby incorporated herein by reference.